1. Field of the Invention
The present invention relates generally to an inspection apparatus for bottle mouth caps, and is directed more specifically to an inspection apparatus which automatically detects the good or bad of screw-on caps by using photoelectric conversion sensors and electrical processors such as a computer or the like.
2. Description of the Prior Art
There are a wide variety of capping methods as well as kinds of caps that are used for bottled products such as spirits, beverages or other fluids. For instance, there are the plug-in type cap that inserts a cork or plastic material into the bottle mouth; or, the screw type wherein the outside of the bottle mouth is formed with a screw thread to which a cap made of metal or plastic that has a threaded screw is screwed thereon. Both types are equally used even for the recycled bottles (e.g., recovered and refilled) in which cases the same bottles are repeatedly used.
On the other hand, the method of using recycled or refilled bottles faces problems such as increases in recovery related costs, as well as the bottle breakages during the market cycle. Consequently, there is a noted increase in the use of the so-called one way bottles which are only used one time, during the recent years.
This trend is not only true for large sized bottles, but can generally be seen in the smaller sized bottles. As a result, the concept relating to the construction of the cap on these one way bottles differs somewhat from the case of the recycle type bottles. That is, in the first place, the cap must be easily openable by hand, and in the second place, the cap must have such a construction that it can be tightly secured onto the bottle mouth and will not easily open until the bottle arrives in the hands of the final user or client.
FIG. 1 shows a side view of one example of a cap C that has such a construction. Further, the cap C is made of metal material as one example. As shown on the same figure, cap C has a screw thread portion C1 which screws on to the screw portion formed on the outer periphery of the bottle mouth, (not shown on the drawing). Continuing from the lower edge of the screw portion C1, there is provided a ring like lower portion C2 that is tightened on to the lower part of the bottle mouth, after the cap C is screwed on to the bottle mouth. When the cap C that is screwed on the bottle mouth is turned in the direction to be un-screwed and taken off, cap C easily detaches from the bottle mouth. However, the lower portion C2 of the cap C contains such a taper that it is larger in diameter going upwards from its lowest edge, and is smaller in diameter as it goes further upwards from its maximum protruding portion. When the cap C is screwed on to the bottle mouth, its lower portion C2 is tightened on to the lower protruding part of the mouth so that it prevents the cap C from loosening as a result of general vibration and the like during shipment and hence the content fluid inside the bottle does not leak away from the bottle mouth, or the cap C cannot detach itself from the bottle mouth.
When the final user of the bottle takes off the cap C, a slight force is applied to the cap C at the start causing the cap C to unscrew. A subsequent force to cause the cap to come off of the bottle mouth is applied to the lower portion C2 of the cap C which remains tightened on the bottle. Since scores (or notches) which will be described later are formed in the lower portion C2, the lower portion C2 is only partially broken from the cap C along some of the scores, after which the cap C easily rotates so that the cap C can be detached from the bottle mouth. To permit the cap C to be easily detached and removed from the bottle mouth, a plurality of horizontal scores C3 are engraved at a predetermined distance along the circumference of the maximum protruding portion of the lower portion C2, and/or connected to such horizontal scores C3, a plurality of vertical direction running scores C4 at a predetermined distance are engraved respectively. Needless to say, the number or sequence of the scores C3 and C4 may vary depending upon the kinds of purposes desired for them.
From a psychological standpoint, when the end user takes the bottle in his hand and visually checks the lower portion C2 of the cap C to confirm that there is no damaged part in the scores C3 or C4, a positive feeling is generated of reliance upon the bottled product. This type of cap C is normally called as the Pilfer Proof Cap (or abbreviated as the PP Cap).
The lower portion of the cap C that is shown on FIG. 1 illustrates that the scored portion C2 is a good product without defects. On the other hand, FIGS. 2A and 2B illustrate an example, with partial magnification of side and top views, where there is a defect in the scored portion C2. In other words, as shown on FIGS. 2A and 2B, one piece C5 between vertical neighbouring scores C4 of the scored portion C2 of cap C has come apart, at one of the vertical scores C4, from the scored portion C2 and protrudes towards the outside of the cap C.
It is, therefore, essential for the maker or bottler that he confirm, after filling the one way bottles with fluid and screwing the above mentioned cap on to the bottle mouth, firstly that the cap does not permit leakage of the fluid and secondly, to especially check whether or not any damage and/or abnormally exist at the scored portion of the cap.
It is now considered as a natural necessity to automate and achieve material labour savings in inspection process in the same manner as automation obtains labour savings advancements in the various production processes.
In relation to inspection automation, various proposals are conventionally made using a variety of sensor types. In one such case, a method to automatically inspect the lower part of a bottle cap is attempted by irradiating light onto the lower part of the cap, from which the reflected light is caught by a photoelectric conversion sensor, detecting the existence of any abnormality in the cap.
However, as mentioned, the lower part of cap C (i.e., the section C2) carrying the score structure, is located lower than the top surface of the bottle mouth. The top surface extends all around the outer periphery of the bottle mouth and at the same time forms one part of the cap C, which further is curved inwardly and downwardly to the lowest edge, so that the inspection of this part in one shot cannot be easily made.